The present invention relates to a unitary fluid flow production and control system in which output pressure of the fluid and flow rate of the fluid can be independently controlled.
Fluid flow development is utilized in a wide variety of systems and for a variety of purposes including, for example, fuel delivery for automobiles, aircraft and other motorized vehicles, water delivery systems, hydraulic systems, pneumatic systems, chemical and petrochemical processes, oil refining, power generation, heating and air conditioning systems, etc. The fluid flow in such systems may be produced using various type pumps such as centrifugal pumps, piston actuated pumps, diaphragm pumps, and the like.
In nearly all fluid flow production systems, two of the parameters or fluid characteristics of interest are flow rate at the output of the pump or other flow developing device, and output pressure of the fluid. It is oftentimes desirable to control, to the extent possible, these two parameters but effectuation of such control such as by varying the speed of operation of the pump, for example, results in controlling either the output flow rate or the output pressure, but not both. In particular, plotting output pressure versus output flow rate for different pump speeds yields a family of curves in which the output pressure decreases as the flow rate increases and vice versa. Furthermore, throttling the discharge of a constant speed pump affects both flow and pressure, but not independently. Of course, independent control and selected variation of each parameter by itself would be desirable.
Exemplary prior art patents describing fluid flow systems, pumps and approaches to controlling operation of the systems include U.S. Pat. Nos. 4,932,840 (control apparatus of variable delivery pumps), 4,801,247 (control of various parameters of a variable displacement piston pump), 3,563,672 (a pump control system for maintaining a substantially constant output pressure), 2,944,488 (a pump control system to maintain a constant pressure in a fluid delivery line downstream of a pump), 4,204,808 (a variable drive pump to maintain a pipe line suction pressure at an acceptable level), 4,257,746 (dosimeter having a low air flow rate), 4,795,314 (condition responsive pump such as a peristaltic blood pump control utilizing integrated, commanded, and sensed flow rate signals), 4,332,527 (variable speed centrifugal pump), and 4,907,950 (variable positive fluid displacement system).